"The women put in the underling position were a lot more likely to laugh at the muffin joke (and others almost as lame) than were women in the control group. But it wasn’t just because these underlings were trying to manipulate the boss, as was demonstrated in a follow-up experiment.
"This time each of the women watched the muffin joke being told on videotape by a person who was ostensibly going to be working with her on a task. There was supposed to be a cash reward afterward to be allocated by a designated boss. In some cases the woman watching was designated the boss; in other cases she was the underling or a co-worker of the person on the videotape.
"When the woman watching was the boss, she didn’t laugh much at the muffin joke. But when she was the underling or a co-worker, she laughed much more, even though the joke-teller wasn’t in the room to see her. When you’re low in the status hierarchy, you need all the allies you can find, so apparently you’re primed to chuckle at anything even if it doesn’t do you any immediate good."
In my books, when something funny happens, I make sure to describe other characters in the book laughing. I've always imagined that it's easier to laugh when others near you are laughing (even if they characters in a book).